Aerojet Rocketdyne, ULA Celebrate 60th Anniversary of RL10 Rocket Engine

A milestone is reached as Aerojet Rocketdyne and ULA commemorate the 60th anniversary of the RL10 rocket engine.


A Legacy of Success

The RL10 engine, which is powered by a combination of liquid hydrogen and liquid oxygen, celebrates 60 years since its debut in space. Manufactured by Aerojet Rocketdyne, the engine made its first flight on November 27, 1963, onboard a Centaur upper stage launched from Cape Canaveral. This achievement came just five days after the assassination of former President John F. Kennedy.

Since its inaugural launch, a total of 522 RL10 engines have been used in space missions. The majority of these engines were flown aboard United Launch Alliance's Delta and Atlas rockets, powering the Delta Cryogenic Second Stage and Centaur upper stage, respectively. The RL10 and Centaur combination has enabled the launch of spacecraft at greater size and weight than other upper stage designs.

Accomplishing missions to destinations ranging from the Sun to asteroids and every planet in the solar system, the RL10 has played a crucial role in advancing space exploration. Originally developed by Pratt & Whitney in the late 1950s, the engine was overseen by NASA's Lewis Research Center, now known as the NASA John H. Glenn Research Center at Lewis Field. Centaur was initially developed by General Dynamics.

The Evolution of the RL10

Currently, two variants of the RL10 are in use: the RL10C-1-1 on ULA's Atlas rockets and the RL10B-2, used on the ULA Delta 4 Heavy and NASA Space Launch System (SLS) rockets. However, the RL10B-2 has a limited lifespan, as there is only one more Delta 4 Heavy rocket scheduled for launch in 2024.

For the first three Artemis missions to the Moon, a single RL10B-2 is being utilized on the SLS's Interim Cryogenic Propulsion Stage (ICPS). Future versions of the SLS will feature the Exploration Upper Stage, powered by four RL10C-3 engines.

Aerojet Rocketdyne has made several major upgrades to the RL10 engine, with eight iterations to date. The next major version, the RL10C-X, is currently in development and will provide higher performance and extended engine life. Additive manufacturing techniques, such as 3D printing, are being incorporated into the engine's production, resulting in cost savings and enhanced capabilities.

The Future of RL10

The RL10C-X engine is expected to debut in 2025 on ULA's Vulcan rocket. The engine will deliver the highest performance and reliability to date, thanks to the implementation of additive manufactured features. The incorporation of 3D printed components, including the thrust chamber, has significantly improved the engine's cost and production efficiency.

Aerojet Rocketdyne currently has a backlog of over 150 RL10 engines, including both legacy versions and those with additive manufactured components. Both NASA and ULA are considering the use of RL10 engines for future Artemis missions, with a determination yet to be made.

The upcoming launch of ULA's Vulcan rocket, powered by RL10C-1-1A engines, will further showcase the capabilities of the RL10. As ULA and Aerojet Rocketdyne continue to collaborate, the RL10C-X engine is expected to play a key role in future missions, including crewed launches as part of the Commercial Crew and Artemis programs.